Christopher Monroe's (University of Michigan, in Ann Arbor) group has taken one of the first steps toward a multilayered trapped ion quantum compute. As reported in the January issue of Nature Physics, his team fashioned a smaller, squatter version of a conventional trap by alternating layers of gallium arsenide and aluminum-gallium-arsenide. The result was an insulating layer sandwiched between two electrode layers. The researchers carved a channel down the chip and etched the flanking regions into individual diving boardshaped pieces. They were able to load a single cadmium ion into the gap between these pieces. To cool and probe the ion, they shone a laser down the central channel.
A major benefit of chip-based ion traps is that they could be combined into large arrays. The goal is to create a big switchyard in which hundreds or thousands of ions are constantly being shuttled around in small groups, controlled by conventional electronics. In the next few years, researchers predict, ion traps will likely be scaled up from a handful of ions to 50 or 100.
Large scale quantum computers would be very useful in enabling large scale quantum simulations that would help in developing molecular nanotechnology.